ARA-290 has an unusual origin: it is a single piece of erythropoietin (EPO) — the hormone best known for making red blood cells — rebuilt so that it does the *opposite* of what EPO is famous for. It does not raise your blood count. Instead it was designed to switch on the body's tissue-repair and anti-inflammatory machinery, which is why it has been studied for nerve damage and chronic inflammation. It is also called cibinetide.
In plain terms: scientists took the "repair" half of a blood hormone and threw away the "make more blood" half.
What it is
ARA-290 is an 11-amino-acid linear peptide copied from the three-dimensional shape of one region of EPO, called helix B5. You may also see it written cibinetide (its official drug name) or pHBSP (pyroglutamate helix B surface peptide) — all the same molecule. EPO itself is a powerful tissue-protective signal, but using EPO as a repair drug is risky, because it also thickens the blood. ARA-290 keeps the protective signal while dropping the blood-making one.
How it is thought to work
The key is that EPO actually talks to two different receptors. One — the receptor most people mean by "the EPO receptor" — drives red-blood-cell production. The other is the innate repair receptor (IRR), a partnership between the EPO receptor and a second protein called CD131 (the β-common receptor)4. The IRR appears on tissues under stress or injury and acts as a master switch for protection and repair3.
ARA-290 is built to bind only the innate repair receptor, not the blood-making one5. Activating it appears to calm over-active immune cells and support nerve and blood-vessel repair — the thread running through everything it has been tested on6.
In plain terms: EPO has a "grow blood" button and a "repair tissue" button. ARA-290 presses only the repair button.
Small-fibre neuropathy — its main target
Small-fibre neuropathy is damage to the tiny nerve endings that carry pain and temperature signals. It causes burning pain, numbness, and — in diseases such as sarcoidosis and diabetes — real disability. Because those fibres are hard to see, researchers measure them in the cornea (the front of the eye is densely supplied with exactly this kind of nerve) using a non-invasive scan1. That is the setting for ARA-290's most-cited human result.
What the studies actually found
ARA-290's evidence is unusual for a research peptide: it includes real, if small, human trials, on top of a wide base of animal work. Note the model in each row.
| Study | Model | Key result | Year |
|---|---|---|---|
| Culver et al. — phase 2b RCT1 | 64 people with sarcoidosis small-fibre neuropathy | 28 days of cibinetide (1, 4, or 8 mg/day) improved corneal nerve-fibre abundance and nerve-regeneration markers versus placebo | 2017 |
| Lois et al. — phase 22 | 9 people with diabetic macular edema | Small exploratory trial, 4 mg/day for 12 weeks — an early test in a diabetic eye complication | 2020 |
| Bitto et al. — preclinical (mice)3 | diabetic (db/db) mice | Daily cibinetide improved diabetic wound healing and raised repair signals (VEGF, phospho-Akt) | 2018 |
| Awida et al. — preclinical (mice)4 | healthy mice | One month of cibinetide raised cortical (~5.8%) and trabecular (~5.2%) bone density via the EPOR–CD131 receptor | 2021 |
| Ghassemi-Barghi et al. — preclinical (cells)5 | kidney cells + cisplatin | ARA-290 reduced kidney-cell toxicity and inflammatory markers (TNF-α, IL-6, IL-1β) | 2023 |
The human headline is the sarcoidosis trial: in 64 people with sarcoidosis-related small-fibre nerve loss and neuropathic pain, 28 days of cibinetide improved measures of corneal nerve-fibre abundance and nerve regeneration versus placebo1. A separate small phase-2 study tested it in diabetic macular edema2. Both are early and small — signals, not proof. In studies it is given as a small daily subcutaneous injection (the doses researchers tested, described here for context, not as a recommendation).
Why "non-hematopoietic" is the whole point
EPO's repair effects have been known for years, but doctors can't simply give EPO for tissue injury: repeated dosing thickens the blood, raising the risk of clots and high blood pressure. ARA-290's entire design is to deliver the repair signal without touching the blood count4. Because it binds the repair receptor selectively, it is not expected to raise red cells or blood pressure the way EPO does. That safety separation — not a bigger effect — is what makes it interesting to researchers.
The wider (mostly preclinical) picture
Beyond the neuropathy trials, most ARA-290 data is in animals and cells, spanning conditions linked by inflammation and tissue stress: it improved wound healing in diabetic mice3, increased bone density in mice4, protected kidney cells from chemotherapy toxicity5, and dampened the immune-cell activity that drives experimental colitis6. These fit the "innate repair" mechanism, but they are early-stage: a mouse result is a reason to run a human trial, not a substitute for one.
Regulatory status
ARA-290 / cibinetide is not an approved medicine. It has been through several small phase-2 trials but has no regulatory approval for any use. This page explains what it is and what the studies showed — not how to use it — and it takes no position on sourcing.
The short version
ARA-290 (cibinetide) is an 11-amino-acid peptide carved from erythropoietin and engineered to activate only its tissue-repair receptor, not the one that makes red blood cells. That design lets it carry EPO's anti-inflammatory, nerve-protective signal without EPO's blood-thickening risk. Its strongest evidence is a small phase-2b trial in sarcoidosis small-fibre neuropathy, backed by broad animal data on repair and inflammation. It is investigational, not approved. For other recovery-focused peptides, see BPC-157 and TB-500. Educational overview only, not medical advice.